JPH04287063A - Cleaner-less type image forming device - Google Patents

Abstract

PURPOSE:To prevent the picture quality of a first sheet from lowering without performing dummy print in a device in which development and the collection of residual toner are performed simultaneously by a developing roller. CONSTITUTION:A photosensitive drum 1 whose surface is covered with a photosensitive material, an electrification charger 2 which electrifies the photosensitive drum 1 according to an electronic photographing process, a exposure part 3 which performs exposure, a developing part 4 which performs the development, and the developing roller 6 which collects the residual toner remaining on the non-exposure part of the photosensitive drum 1 by coming in contact with the surface of the photosensitive drum 1 to the developing part 4 and also, attaches toner 8 on the exposure part are provided. Such control that the operation of the exposure part 3 is prohibited prior to the start of the print of the first sheet, and the photosensitive drum 1 and the developing roller 6 can be rotated is performed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleanerless image forming apparatus that does not have a residual toner cleaning device.

0002

2. Description of the Related Art An image forming apparatus, such as a laser printer, charges a photoreceptor of a photoreceptor drum in a charging section, and records information on the charged photoreceptor by exposing it to a laser beam to form a static latent image. Toner is attached to this electrostatic latent image in a developing section, and the toner image is transferred onto paper in a transfer section. Then, the paper onto which the toner image has been transferred is thermally fixed in a fixing section to complete printing. Further, after the transfer, the toner remaining on the photoreceptor drum is removed by a cleaning device, and the photoreceptor is further neutralized to prepare for the next charging.

Recently, in order to reduce the size and cost of laser printers, cleaning devices for removing toner remaining on the photoreceptor after transfer have been abolished.
So-called cleanerless laser printers are becoming popular. This cleanerless type is, for example, published in Japanese Unexamined Patent Publication No. 59
- As seen in Japanese Patent No. 133573, a developing roller is brought into contact with a photoconductor, and at the same time, the developing roller attaches toner to the photoconductor, and at the same time collects residual toner that was previously used for development and remained without being transferred. ing.

0004

[Problems to be Solved by the Invention] However, in the system in which toner is attached to the photoconductor using a developing roller and residual toner is collected at the same time, the residual toner is collected at the same time as when the toner is deposited on the photoconductor by the developing roller. When printing eyes, it is not possible to remove the toner adhering to the photoreceptor from the developing roller before exposure before the exposed area of the photoreceptor reaches the developing section, so there is a problem that the exposure is blocked and the image quality deteriorates. there were.

[0005] For this reason, it is conceivable to use the first sheet as a dummy and print it in white to transfer the residual toner onto the paper, but if this is done, there is a problem that wasteful printing always occurs at the beginning.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a cleaner-less image forming apparatus that can prevent the image quality from deteriorating on the first sheet without performing dummy printing, in which development and residual toner collection are performed simultaneously using a developing roller. It is something to do.

[0007]

[Means for Solving the Problems] The present invention exposes a photoreceptor charged in a charging section to light in an exposure section to form a static latent image,
At the developing section, a developing roller is brought into contact with the photoconductor to adhere toner to the electrostatic latent image, and residual toner is collected from the photoconductor, and the toner image formed on the photoconductor is transferred to paper at the transfer section to form an image. In a cleaner-less image forming apparatus, before printing the first sheet, the potential of the photoconductor and the potential of the developing roller are set to predetermined potentials necessary to collect residual toner on the photoconductor. It is provided with control means for rotating the body at least once.

[0008]

[Operation] In the present invention having such a configuration, the photoreceptor and the developing roller are cleaned of residual toner on the photoreceptor before starting printing of the first sheet, for example, at the start of printing or after recovery from a jam. is set to a predetermined potential necessary to recover the sample and rotated at least once. As a result, toner that is initially attached to the photoreceptor from the developing roller and does not contribute to transfer is collected by the developing roller as residual toner. Thereafter, the photoreceptor is charged, exposed, developed, and transferred to start image formation.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a photoreceptor drum whose surface is covered with a photoreceptor, and this photoreceptor drum 1 is driven to rotate clockwise as shown by an arrow in the figure. Around the photosensitive drum 1, a charging charger 2, an exposure section 3, a developing section 4, and a transfer charger 5 are arranged according to an electrophotographic process. The charger 2 uniformly charges the photoreceptor of the photoreceptor drum 1.

The exposure section 3 irradiates the photoreceptor of the photoreceptor drum 1 with a laser beam 3a from, for example, a laser scanner unit (not shown) based on recorded information, and forms a static latent image of the information by exposure. It has become.

The developing section 4 is provided with a developing roller 6 in contact with the surface of the photoreceptor drum 1, and rotates the developing roller 6 in the direction of the arrow in the figure to remove the remaining portion of the photoreceptor drum 1 from the non-exposed area. At the same time, the toner 8 contained in the storage container 7 is attached to the exposed portion to form a toner image.

The transfer charger 5 applies a desired voltage to the paper 9 being conveyed in the direction of the arrow in the figure, thereby transferring the toner image from the photosensitive drum 1 onto the paper 9. Note that the paper onto which the toner image has been transferred is then thermally fixed, for example, by a fixing device (not shown).

FIG. 2 is a block diagram showing the main circuit configuration.
11 is a CPU (central processing unit) that constitutes the main body of the control unit;
12 is a program ROM (read only memory) in which program data for the CPU 11 to control each part is stored; 13 is a work area for data processing and information for printing is stored as an expanded image. 14 is an interface for exchanging information with a host computer and receiving print information from the host computer; 15 is an operation panel equipped with various keys, lamps, etc.; A mechanism control circuit 17 for driving and controlling the photosensitive drum 1, charger 2, laser scanner unit, developing roller 6, transfer charger 5, etc. according to the electrophotographic process sends print data to the mechanism control circuit 16. Control output for each line and the operation panel 15
It is an interface and a 1-line buffer memory that takes in key signals from the main unit and outputs display signals.

The CPU 11 causes the photosensitive drum 1 and the developing roller 6 to rotate, for example, once before starting printing the first sheet at the start of printing or when recovering from a jam (paper jam). It has become. At this time, the operation of the laser scanner unit is prohibited.

For example, in the case of reversal development in which the photoreceptor drum 1 is negatively charged, the developing bias potential applied to the developing roller 6 is negative, for example -250V, in a normal printing process, and the potential of the photoreceptor drum 1 is is set to a deeper negative potential such as -500V, for example. In this case, a toner having a characteristic of being easily negatively charged is used.

When the photosensitive drum 1 and the developing roller 6 are rotated once before starting printing of the first sheet, if the charger 2 is not operated, the CPU 11 controls the photosensitive drum 1 and the developing roller 6. The potential of the developing roller 6 is maintained at 0, that is, the ground potential.
The potential of the photoreceptor is maintained at a predetermined potential necessary for recovering the residual toner on the photoreceptor, for example, +200V.

When the charger 2 is operated, only exposure by the laser scanner unit is prohibited. In this case, the developing bias potential is -250V, and the potential of the photosensitive drum 1 is -500V.

In the embodiment with such a configuration, for example, when the charger 2 is not operated, the developing bias potential applied to the developing roller 6 is +200V, the potential of the photosensitive drum 1 is set to 0V, and the first sheet is Prior to starting printing, the photosensitive drum 1 and the developing roller 6 are rotated once. As a result, the negatively charged residual toner is collected and cleaned by the developing roller 6, which has a relatively positive potential.

In this manner, prior to the start of printing, the photoreceptor drum 1 rotates once and the toner adhered to the photoreceptor drum 1 from the developing roller 6 is collected by the developing roller 6 as residual toner. When the printing operation is started and the photosensitive drum 1 is charged and exposed, the exposure is no longer blocked by residual toner. Therefore, exposure is performed normally and deterioration in print quality is prevented. Furthermore, dummy printing is not required, and no paper is wasted.

For example, when operating the charger 2, the developing bias potential applied to the developing roller 6 is -
250V, and the charging potential of the photoreceptor drum 1 is set to -500V, and the photoreceptor drum 1 and the developing roller 6 are rotated once before starting printing of the first sheet. As a result, the negatively charged residual toner is collected and cleaned by the developing roller 6, which has a relatively positive potential.

Therefore, in this case as well, the toner attached to the photoreceptor drum 1 is collected as residual toner by the developing roller 6, so the normal printing operation is started after one rotation and when the photoreceptor drum 1 is charged and exposed, it is exposed. is no longer blocked by residual toner. Therefore, exposure is performed normally and deterioration in print quality is prevented. In this case as well, dummy printing is not required and paper is not wasted. The above operation is performed not only at the start of the printing operation, but also when a jam occurs and the cause of the jam is subsequently removed and the printing operation is restarted.

Further, during normal printing, as shown in FIG. 3, the developing bias potential Vb applied to the developing roller 6
is -250V, and the charged potential V0 of the photosensitive drum 1 is -
Since the voltage is 500V, the negatively charged residual toner in the non-exposed area is -
The toner is collected by the developing roller 6, which is charged to 500 V and has a relatively positive potential, and is cleaned. Furthermore, since the negatively charged toner in the exposed area has dropped to approximately 0V due to exposure, the negatively charged toner charged to -250V by the developing roller 6 is attracted and adhered to the exposed area of the photoreceptor drum 1. In this way, collection of the negatively charged residual toner in the non-exposed area and adhesion of the negatively charged toner from the developing unit 4 to the exposed area of the photoreceptor drum 1 are performed simultaneously.

[0024] In the above embodiment, the photosensitive drum 1 is
Although the residual toner is collected by rotating, the present invention is not limited to this, and two or more rotations may be used.

[0025]

Effects of the Invention As detailed above, according to the present invention, a cleaner is provided that can prevent the image quality from deteriorating on the first sheet without performing dummy printing in a device that simultaneously performs development and collects residual toner using a developing roller. Accordingly, it is possible to provide a wireless image forming apparatus.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of main parts showing an embodiment of the present invention.

FIG. 2 is a block diagram showing the main circuit configuration of the same embodiment.

FIG. 3 is a diagram for explaining the principle of simultaneous development and cleaning in the same embodiment.

[Explanation of symbols]

1... Photosensitive drum, 2... Charger, 3... Exposure section,
4...Developing section, 5...Transfer charger, 6...Developing roller, 8
...Toner, 11...CPU.

Claims (1)

[Claims] 1. A photoconductor charged in a charging section is exposed to light in an exposure section to form a electrostatic latent image, and a developing roller is brought into contact with the photoconductor in a developing section to adhere toner to the electrostatic latent image. At the same time, residual toner is collected from the photoreceptor, and the toner image formed on the photoreceptor is transferred to paper in a transfer section to form an image. In the cleanerless image forming apparatus, printing of the first sheet is started. The method further comprises a control means for setting the potential of the photoreceptor and the potential of the developing roller to predetermined potentials necessary to collect residual toner on the photoreceptor and rotating the photoreceptor at least once. A cleaner-less image forming device.